Instructional Time and Student Achievement

The Question
What is the relationship between instructional time and student achievement?that is, does increasing instructional time increase achievement?

The Context
Many variables in education can be analyzed in an effort to determine their role in student learning: teacher quality, curriculum, school funding, classroom management, and so on. Most of these variables relate to the relationship between the student and the curriculum. In other words, how can educational structures be constructed in such a way as to facilitate access to the curriculum for students? One of the chief variables, when the question is phrased this way, is the actual time that students spend engaged with the curriculum. Within this context, time can refer to the number of days in school, hours in courses, or even minutes on task. Prior research has shown a ?summer learning loss? (see ResearchBrief Volume 1, Number 14 and ResearchBrief Volume 2, Number 14) that has caused some educators and policymakers to call for year-round schooling or summer school for low-achieving and at-risk students. The push for year-round schooling is not universal, however, and has even generated an active opposition that worries about the type of unmeasured?but still important?learning that may be lost if the summer break is eliminated. Time as a resource has also been the focus of block scheduling research, which looks at the efficacy of expanding the blocks of time students are in contact with specific curricula (see ResearchBrief Volume 2, Number 10). This issue of ResearchBrief looks at the question of instructional time and its effect on student learning across nations.

The Details
David Baker, Rodrigo Fabrega, Claudia Galindo, and Jacob Mishook conducted the study highlighted in this issue of ResearchBrief (see below for full citation). Their goal was to examine the time various countries allocated to the school year across four subject areas?math, science, civics, and language?to see if a relationship existed between time spent in school and student achievement. The researchers looked at three international assessments conducted between 1999 and 2000: the Programme for International Student Assessment (PISA), the 8th-grade-focused Trends in International Math and Science Survey (TIMSS), and the International Study of Civic Education (CIVED). The number of countries covered by each assessment ranged from 28 (CIVED) to 38 (TIMSS), allowing for analysis of 52 countries (some of which had data across multiple tests). Although each assessment covered different subjects and age groups, they all included questions that asked respondents to note the weeks in a school year, the classes in a week, and the minutes in a class, allowing the researchers to construct the amount of time students spent in a particular subject area.

Mexico and Austria required the most instructional time in hours per year, at more than 1,100, whereas Greece required less than 800 hours of total instructional time (the United States required just under 1,000 hours). The amount of time spent on any given subject did not seem to correlate to total hours of instruction. Most countries offered between three and four hours of math instruction, irrespective of total instructional hours. Indonesia and Morocco required more than five hours of math instruction, and no country required less than two hours of math instruction. Ultimately, the authors found no correlation between total hours of instruction and specific achievement test scores.

The authors next analyzed the effect of variations in total instructional time within nations by comparing total instructional hours to math, science, and civics achievement. The variance in achievement was only slightly related to total instructional hours. In Japan, for example, students who received more than 1,112 hours of instruction per year scored only 25 points higher on the math assessments than those who received less than 935 hours of total instruction. The majority of countries generally showed small correlations between total hours of instruction and achievement scores in math. The same held true for achievement in science and civics.

The authors also examined the relationship between the hours of subject-specific instruction and subject-specific achievement and again found weak correlations. In math, the average variation in achievement explained by instructional time was +/- 0.14 (or only 2.2 percent of the variation in scores). In science there was a slightly stronger correlation of .23, explaining 5.0 percent of the variation in scores; while in civics, two countries showed a positive correlation, but six countries showed a negative correlation. At best, the average variance in score explained by increasing the hours of instruction ranged from 0.8 percent in math to 7.0 percent in civics (most notably among developing nations).

The Bottom Line
Changes in instructional time do not generally increase or decrease student achievement, unless such changes go beyond unusually low, or high, amounts of time. Curriculum and instructional quality appear to have a much greater effect on achievement than do total hours of instructional time.

Who's Affected?
This study looked at the likely effect of instructional time on student achievement, both within nations and across nations.

Caveats
This research looks at the correlations between hours of instructional time and achievement. While it is tempting to assume that there is a causal relationship between hours of instructional time and achievement, we cannot assume that based on this study. For example, within some nations, as instructional time increases, achievement decreases. Is it the increase in instruction that causes the decrease? We can?t tell. For example, it could be that schools with high populations of lower-achieving students offer more instruction to help increase scores. The study also did not examine the quality of instruction students received within the hours of instruction analyzed. In other words, the researchers did not examine what was actually done in the time allocated to each subject. Further, although simply increasing the time that students are exposed to specific subjects does not seem to be an approach that positively improves student performance, the variation between nations, and within nations, was limited, leaving open the possibility that greater variations in time allotments might have a greater effect on achievement. It is also important to note that for some countries, there was actually a negative correlation between increased total hours of instruction, or increased subject-specific hours of instruction, and student achievement.